Development of human kidney begins in: March 2002
**Core Concept**
The development of the human kidney is a complex process that begins early in embryonic development. It involves the formation of the metanephric blastema, which differentiates into the renal cortex, medulla, and calyces. This process is crucial for the formation of a functional kidney.
**Why the Correct Answer is Right**
The development of the human kidney begins in the 5th week of gestation, when the ureteric bud emerges from the mesonephric duct and interacts with the metanephric blastema. This interaction leads to the formation of the renal cortex and medulla. The metanephric blastema differentiates into the nephrons, which are the functional units of the kidney. The ureteric bud forms the collecting ducts, calyces, and renal pelvis. This process is essential for the formation of a functional kidney.
**Why Each Wrong Option is Incorrect**
**Option A:** This is not a valid choice.
**Option B:** This is not a correct answer. While the development of the kidney does involve the metanephric blastema, it is not the correct answer to the question.
**Option C:** This is not a correct answer. The development of the kidney begins before the 6th week of gestation.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that the development of the kidney begins early in embryonic development, and any abnormalities in this process can lead to congenital anomalies of the kidney and urinary tract (CAKUT).
**Correct Answer:** A. 5th week of gestation